It is rare that we feel ourselves to be participating in history. Yet, as Bertrand Russell observed, philosophy develops in response to the challenges of socio-cultural problems and situations. The present-day philosophical endeavor is prompted not by one or two, but by a conundrum of problems and controversies in which the forces carrying life are set against each other. The struggles in which contemporary mankind is fiercely engaged are not confined, as in the past, to economic, territorial, or religious rivalries, nor to the quest for power, but extend to the primary conditions of human existence. They under­ mine man's primogenital confidence in life and shatter the intimacy of his home on earth. Philosophical reflection today cannot fail to feel the pressure of the current situation within which it unfolds. Since this situation now involves the ultimate conditions of human existence, its demands have at last given to philosophy the impetus and direction needed for conceiving that the first and last of its concerns should be life itself.